Collectanea Botanica vol. 32 (2013): 59–82 ISSN: 0010-0730 doi: 10.3989/collectbot.2013.v32.006 New xenophytes from Gran Canaria (Canary Islands, Spain), with emphasis on naturalized and (potentially) invasive species F. VERLOOVE National Botanic Garden of Belgium, Domein van Bouchout, B-1860 Meise, Belgium E-mail: [email protected] Editor: N. Ibáñez Received 19 February 2013; accepted 15 April 2013 Abstract NEW XENOPHYTES FROM GRAN CANARIA (CANARY ISLANDS, SPAIN), WITH EMPHASIS ON NATURALIZED AND (POTENTIALLY) INVASIVE SPECIES.— Recent fieldwork in Gran Canaria yielded several interesting new records of non-native vascular plants. Agave attenuata, Antigonon leptopus, Atriplex nummularia, Cascabela thevetia, Cenchrus echinatus, Cuscuta campestris, Diplachne fusca subsp. uninervia, Diplotaxis tenuifolia, Dysphania anthelmintica (hitherto confused with D. ambrosioides), Eclipta prostrata, Euphorbia pulcherrima, Fagopyrum esculentum, Gossypium barbadense, Lablab purpureus, Lemna minuta, Opuntia leucotricha, Passiflora edulis, Pennisetum glaucum, Phaseolus acutifolius, Pluchea carolinensis, Prosopis juliflora, Salvia microphylla, Schinus terebinthifolius, Senna spectabilis, Solanum chrysotrichum, Tecoma stans, Tipuana tipu, Urochloa mutica, U. plantaginea and Washingtonia robusta are reported for the first time from the Canary Islands, while Alopecurus myosuroides, Amaranthus blitoides, Bothriochloa ischaemum var. songarica, Cardamine flexuosa subsp. debilis, Heliotropium curassavicum, Leonotis nepetifolia, Medicago lupulina, Parkinsonia aculeata, Physalis peruviana, Phytolacca americana and Turnera ulmifolia are new to the flora of the island of Gran Canaria. Finally, both Paspalum vaginatum and P. distichum and Cortaderia selloana are confirmed from Gran Canaria. Key words: Canary Islands; chorology; Gran Canaria; new records; vascular plants; xenophytes. Resumen NUEVOS XENÓFITOS DE GRAN CANARIA (ISLAS CANARIAS, ESPAÑA), CON ÉNFASIS EN LAS ESPECIES NATURALIZADAS Y (POTENCIALMENTE) INVASORAS.— Trabajos recientes de campo en Gran Canaria han facilitado el descubrimiento de nuevas localidades para plantas vasculares no nativas. Agave attenuata, Antigonon leptopus, Atriplex nummularia, Cascabela thevetia, Cenchrus echinatus, Cuscuta campestris, Diplachne fusca subsp. uninervia, Diplotaxis tenuifolia, Dysphania anthelmintica (hasta ahora confundida con D. ambrosioides), Eclipta prostrata, Euphorbia pulcherrima, Fagopyrum esculentum, Gossypium barbadense, Lablab purpureus, Lemna minuta, Opuntia leucotricha, Passiflora edulis, Pennisetum glaucum, Phaseolus acutifolius, Pluchea carolinensis, Prosopis juliflora, Salvia microphylla, Schinus terebinthifolius, Senna spectabilis, Solanum chrysotrichum, Tecoma stans, Tipuana tipu, Urochloa mutica, U. plantaginea y Washingtonia robusta se citan por primera vez para las Islas Canarias, mientras que Alopecurus myosuroides, Amaranthus blitoides, Bothriochloa ischaemum var. songarica, Cardamine flexuosa subsp. debilis, Heliotropium curassavicum, Leonotis nepetifolia, Medicago lupulina, Parkinsonia aculeata, Physalis peruviana, Phy- tolacca americana y Turnera ulmifolia son nuevas para la flora de la isla de Gran Canaria. Finalmente, se confirma la presencia de Paspalum vaginatum, P. distichum y Cortaderia selloana en Gran Canaria. Palabras clave: corología; Gran Canaria; Islas Canarias; nuevas citas; plantas vasculares; xenófitos. 60 F. VERLOOVE INTRODUCTION vate herbarium of the author. Acronyms follow the Index Herbariorum (Thiers, 2013). The vascular flora of the Canary Islands in general, The current presence or absence on the island of and the island of Gran Canaria in particular, has Gran Canaria of the non-native taxa here presented been the subject of numerous publications in the was each time compared with data provided by Ho- past. Eriksson et al. (1974) provided a checklist for henester & Welss (1993) and Acebes Ginovés et al. the whole of Macaronesia and subsequently cho- (2004, 2009). For some recently introduced species rological, taxonomical and nomenclatural updates several additional papers were checked as well. were regularly published (see for instance Hansen The present paper is divided into two parts: the & Sunding, 1993). A similar checklist, but restricted first part deals with naturalized or (potentially) in- to the Canary Islands, was recently published by vasive species, the second one with (presumably) Acebes Ginovés et al. (2004, 2009). Information on ephemeral aliens. In each part taxa are presented non-native (predominantly invasive) species from in alphabetical order, but only in the first part the Canary Islands was provided by Sanz Elorza et additional information is provided. There, each al. (2004a, 2005) and García Gallo et al. (2008). entry includes the scientific name of the taxon (if Despite this ongoing research on the Canarian flora, useful accompanied by one or more synonyms), new data still come to light. Particularly the non- the family to which the taxon belongs (see below), native flora obviously is still imperfectly known kind of chorological novelty and estimated degree and the number of new introductions (deliberate of naturalization (sensu Richardson et al., 2000), as well as accidental) still seems to be increasing. enumeration of herbarium collections, origin of the Elton (1958) already suggested that islands were taxon and details about its secondary distribution particularly prone to invasion because the paucity and, finally, information on its present occurrence in of species in island communities reduced their the island of Gran Canaria. For ephemeral records in ability to resist invaders. This point of view was the second part only herbarium data are referred to. subsequently confirmed by numerous studies in the Familial and generic circumscriptions are in intervening decades. Denslow et al. (2009) recently accordance with APGIII (2009) and Chase et al. summarized why islands are more vulnerable than (2009). Authorities of plant names follow IPNI comparable mainland areas: high habitat diversity, (2013). disharmonic floras, low biotic resistance, high re- source availability and mild climates. In the present paper new records are presented RESULTS for species that are either new to the Canary Is- Naturalized and/or (potentially) invasive species lands (or even Macaronesia) or new to the island of Gran Canaria, and emphasis is put on species Amaranthus blitoides S. Watson in Proc. Amer. that are either naturalized or potentially invasive. Acad. Arts 12: 273 (1877) (Amaranthaceae). Records of (presumably) ephemeral introductions (mostly occasional garden escapes) are only briefly Spain, Gran Canaria: Cercados de Espinos (El dealt with. Horno), barranco de Arguineguín, dry gravelly riverbed, locally not rare, 8.11.2011, F. Verloove 9156 (LPA 28381); El Tablero, Caserío de la MATERIALS AND METHODS Media Fanega, dry gravelly riverbed, very com- The records here presented are the result of five mon, 17.11.2011, F. Verloove 9161 (LPA 28383); weeks of fieldwork in Gran Canaria in November Tamaraceite, barranco N of the city, dry gravelly 2011, November 2012 and March 2013. Voucher riverbed, very common, 4.11.2012, F. Verloove specimens of all taxa are preserved at the public 9880 (LPA 28384). herbaria of the Jardín Botánico Canario Viera y Clavijo in Las Palmas de Gran Canaria (LPA) and/ Origin: North America. or the National Botanic Garden of Belgium (BR). Known distribution in the Canary Islands: known Duplicates were often deposited in other relevant so far from Tenerife and Lanzarote (Acebes Ginovés herbaria (mainly LG, MA and ORT) or in the pri- et al., 2009). Collectanea Botanica vol. 32 (2013): 59–82, ISSN: 0010-0730, doi: 10.3989/collectbot.2013.v32.006 New xenophytes from Gran Canaria 61 Figure 1. Antigonon leptopus, Bañaderos, roadside, November 2012 (Photograph: F. Verloove). Degree of naturalization: naturalized. Origin: Mexico and Central America. Widely Amaranthus blitoides was repeatedly recorded in cultivated as an ornamental (coral vine) in subtro- widely scattered localities in Gran Canaria, often in pical regions of the world. abundance. It must have been overlooked so far, espe- Known distribution in the Canary Islands: never cially in the surroundings of Maspalomas. In addition recorded before (cf. Acebes Ginovés et al., 2009). to the localities cited above, A. blitoides was also seen Degree of naturalization: escaped (naturalized?). in the barranco towards Los Palmitos Park, and in a barranco W of San Fernando (Maspalomas). In the Antigonon leptopus is locally cultivated as an northernmost part of the island it was also recorded ornamental vine in Gran Canaria. In Bañaderos it in abundance in an exposed pond near El Toscón (Las grows abundantly on rough ground, either as an Mesas), on rough ground in the city center of Teror, escape from cultivation or as a garden throw-out. It and in barranquillo de Dios in Marzagán. seems firmly established and a further spread is not Amaranthus blitoides obviously is fully natura- unlikely. In many regions worldwide it is considered lized in Gran Canaria, predominantly in gravelly, a very troublesome, invasive weed (see Burke & dry (but temporarily wet) habitats, especially in DiTommaso, 2011 for a recent detailed overview). barrancos. Atriplex nummularia Lindl., J. Exped. Trop. Aus- Antigonon leptopus Hook. & Arn., Bot. Beechey tralia: 64 (1848) (Fig. 2) (Amaranthaceae s. l.). Voy.: 308 (1838) (Fig. 1) (Polygonaceae). Spain, Gran Canaria: Bahía Feliz, Aeroclub de Spain, Gran